School of Physics Lecture Demonstration Manual

Oc-1 Measurement of the Wavelength of Light Using a Ruler

Published: Wednesday 15 March 2006 - Updated: Monday 28 March 2011

Aim

To obtain a measurement of the wavelength of light using diffraction markings on a ruler.

Apparatus

Diagrams

Click on pictures to enlarge.

Measuring Lamda equation

wavelength Measurement with ruler Diagram

Description

The experimental setup shown above uses the half mm markings as a reflection grating. By measurement of the distance to the image and the distance between interference maxima simple calculation yields lambda.

Taking O as the origin (the mid point between the zeroth order specularly reflected beam and the direct beam) the condition for constructive interference is given by the equation above.

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